An Experimental Study to Probe Defect Formation and Failure Mode in Dissimilar Spot Joints

Expulsion is a familiar occurrence in the resistance spot weldingWelding process, which deteriorates the weld quality. Among various parameters, applied pressure significantly impacts in the expulsion of molten metal, which is undesirable. To understand the influence of electrode pressureElectrode pressure on joint strength and mode of failure, thin sheets of Ti-6Al-4 V and SS316L are welded together in overlapped conditions using the RSW process at varying electrode pressureElectrode pressure of 3, 4, 5, and 6 kg/cm2, keeping other parameters constant. Further, joint strength and mode of failure are investigated. The results showed that with an increase in electrode pressureElectrode pressure to an optimum value, i.e., 3–5 kg/cm2, the strength of the weld joint is enhanced. In contrast, increasing electrode pressure beyond the optimum value leads to the expulsion of material, which restricts the nugget growth, leading to a reduction in joint strength.